Oocyte morphology does not correlate with fertilization rate and embryo quality after intracytoplasmic sperm injection.

Abstract

The fertilization rates and further development of 528 human metaphase II oocytes directly injected by a single spermatozoon were analysed with respect to their morphological features at the light microscopy level at the time of retrieval. The deviations of oocyte morphology which were most frequently observed, after removal of cumulus cells, were dark incorporations, dark zona pellucida, large perivitelline space, spots, vacuoles, refractile bodies and irregular shape. These deviations correlated neither with the fertilization rate nor with the embryo quality score, as compared to 'ideal' oocytes. Since the majority of oocytes displayed deviations from the 'ideal' morphotype but were still fertilized and developed in culture at a normal rate, they were probably as normal as 'ideal' oocytes. Since some of these morphotypes, such as refractile bodies, have been shown to be associated with failure of fertilization, it seems that intracytoplasmic sperm injection may be an appropriate method of treatment for couples in whom repeated failure of in-vitro fertilization is associated with the retrieval of dysmorphic oocytes in the presence of normal semen characteristics.